JP2001291802A - Wiring board and method of manufacturing the same and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board useful for a COB type device and capable of forming a highly reliable electric connection. SOLUTION: This wiring board has a pad for mounting an electronic component electrically connected to the electronic component at one end thereof and lead wiring connected to an external connection terminal at the other end. This wiring board is constructed such that an undercoat layer with low elasticity composed of a material having elasticity lower than that of a substrate is disposed between the base material of the wiring board and each of the pad for mounting an electronic component and the lead wiring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for mounting electronic components, and more particularly, to a wiring board on which electronic components can be mounted by a COB (chip-on-board) method, a method of manufacturing the same, and such a wiring board. And a semiconductor device using the same. Here, the term "electronic component", when used in the specification of the present application, means various components that can be mounted on a wiring board.
Refers to semiconductor elements such as SI chips, passive elements, and power supplies. Therefore, the semiconductor device of the present invention can also be called an electronic device.

[0002]

2. Description of the Related Art Recently, in the field of electronic devices such as personal computers, mobile phones, and PHSs, there is a great demand for downsizing, thinning, lightening, and high functionality of devices. In response to such demands, a technique for mounting a semiconductor element on a wiring board at a high density has been developed and put to practical use.

[0003] Various techniques are already known as high-density mounting techniques, and one of them is a flip-chip method. In the flip-chip method, when a semiconductor element is electrically connected to and mounted on a wiring board, wiring is complicated, and a conductive wire that cannot cope with a complicated structure is not used. A semiconductor element is directly mounted with a metal bump interposed between the terminal and the connection terminal. When the heat treatment is performed to melt the metal bumps, the pads of the wiring board and the external connection terminals of the semiconductor element can be fixedly connected to each other. By the way, in the case of this method, at the time of heating for melting the metal bump, there is a problem that thermal stress caused by a difference in thermal expansion coefficient between the wiring board and the semiconductor element is concentrated on the metal bump and the bump itself is damaged. is there.

[0004] In order to solve the above-mentioned problems, it is often practiced to relieve the stress by improving the package.
For example, there is a method of fixing a pad of a wiring board and an external connection terminal of a semiconductor element with a metal bump, and then filling a resin between the wiring board and the semiconductor element. This method is called an underfill structure, in which the mechanical strength of the metal pump is compensated for by the mechanical strength of the resin, and the breakage of the bump can be prevented. However, in this method, since the thermal stress is not prevented from being concentrated on the bump, it is impossible to completely avoid the damage of the bump.

In order to prevent the thermal stress from being concentrated on the bumps, a method of disposing a sheet-like thermosetting resin-based adhesive between the wiring substrate and the semiconductor element, instead of filling the resin between them, is proposed. There is also. In this method, after a semiconductor element is arranged on a wiring substrate via an adhesive, the semiconductor element is thermocompression-bonded, and the adhesive is cured while the metal pump is connected to a pad of the wiring substrate. When the temperature returns to the room temperature, a compression force such as a heat shrinkage force is generated in the cured adhesive, and the compression force causes the metal pump to be pressed against the pad of the wiring board.
In this method, since the terminal of the semiconductor element and the pad of the wiring board are not fixed via the metal pump, it is possible to prevent the thermal stress from being concentrated on the metal bump due to the difference in the coefficient of thermal expansion between the two. However, in this method, when the thermal expansion coefficient of the adhesive is larger than that of the metal bump, a gap occurs between the bump and the pad during the temperature cycle test, and a connection failure between the two occurs. There is a point.

In order to improve the connection reliability between the pads of the wiring board and the metal bumps, a semiconductor device as shown in FIG. 13 is proposed in Japanese Patent Application Laid-Open No. Hei 10-270496. In this semiconductor device, a semiconductor chip 60 is mounted on a mounting surface of a wiring substrate 51 having a rigid substrate 52 via an adhesive 66.
The external connection terminal 63 is connected to the pad 54A of the wiring board 51 via the bump electrode 65. Particularly, in the case of the illustrated semiconductor device, a recess 54B is formed in the pad 54A, and the pad 54A and the bump electrode 65 are connected in the recess 54B. The pad 54A is made of a flexible layer 53
And a recess 54B of the pad 54A.
Is formed by elastic deformation of the pad and the flexible layer 53. The flexible layer 53 is formed of an epoxy-based low-elastic resin having a lower coefficient of thermal expansion than the adhesive. When such a configuration is employed, the gap between the wiring board 51 and the semiconductor chip 60 can be reduced by an amount corresponding to the amount of depression of the concave portion 54, and thus, as a result of reducing the thickness of the adhesive, Since thermal expansion in the thickness direction of the material can be reduced, it is possible to prevent the occurrence of connection failure during a temperature cycle test.

[0007]

As described above, methods useful for improving the connection reliability between the pads and the metal bumps of the wiring board have been widely studied and proposed. However, all of these methods rely on the improvement of the structure of the package to relieve the stress, so that the structure is complicated, and the manufacturing process is accordingly complicated, and the manufacturing cost is increased.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wiring board capable of increasing the connection reliability between pads of the wiring board and electronic components such as semiconductor chips without complicating the structure and manufacturing. is there. Another object of the present invention is to provide a method suitable for manufacturing such a wiring board.

Still another object of the present invention is to provide a semiconductor device using such a wiring board. The above and other objects of the present invention can be easily understood from the following detailed description.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, the conductors on the wiring board have been improved by improving the wiring board instead of the package. The inventors have found that it is effective to make a pattern (leading wiring) movable to achieve an intended purpose, and have completed the present invention.

The present invention is a wiring board having, on one surface thereof, an electronic component mounting pad for electrically connecting an electronic component at one end, and a lead-out wiring having the other end connected to an external connection terminal. A low-elastic underlayer made of a material having a lower elastic modulus than the base material is interposed between the base material of the wiring board and each of the electronic component mounting pad and the lead-out wiring. Characteristic wiring board.

According to another aspect of the present invention, there is provided a method of manufacturing a wiring board according to the present invention, the method comprising the step of: exposing the external connection terminal formed on a base material of the wiring board. After forming a low elastic base layer made of a material having a lower elastic modulus than the base material, on the low elastic base layer, the electronic component mounting pad and the lead-out wiring in a predetermined pattern respectively Forming,
A method of manufacturing a wiring board characterized by the following.

In another aspect, the present invention is directed to a method of manufacturing a wiring board according to the present invention, wherein a material having a higher elastic modulus than the base material is provided on the base material of the wiring board. After forming a high elasticity underlayer made of a material having a lower elastic modulus than the base material, a low elasticity underlayer made of a material having a lower elastic modulus A pattern in which the electronic component mounting pad, the lead-out wiring, and the external connection terminal are respectively defined by sequentially forming in the same region as the base layer and then selectively removing the conductive metal layer. In a method of manufacturing a wiring board.

Still another aspect of the present invention is a method of manufacturing the wiring board of the present invention,
After forming a low-elastic base layer made of a material having a lower elastic modulus than the base material on the base material of the wiring board, a high-elastic base layer made of a material having a higher elastic modulus than the base material is formed. By sequentially forming a conductive metal layer in a region narrower than the region of the low elasticity underlayer and in a region substantially the same as the low elasticity underlayer, and then selectively removing the conductive metal layer, A method for manufacturing a wiring board, comprising: forming an electronic component mounting pad, the wiring, and the external connection terminal in a predetermined pattern.

Still another aspect of the present invention provides a semiconductor device including, on another side thereof, the wiring board of the present invention, and an electronic component mounted on the wiring board by being electrically connected to the pad. In the device.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A wiring board according to the present invention is one in which electronic component mounting pads for electrically connecting electronic components, routing wiring and external connection terminals are formed on a mounting substrate. Here, the term “routing wiring”, when used in the specification of the present application, is used in a broad sense, and as will be apparent from the following description, various conductive metals provided on a wiring board for wiring purposes. Means a pattern, thus
Hereinafter, they are also referred to as “conductor portion”, “wiring layer”, “wiring pattern”, and the like. In addition, such routing wiring is usually provided on the front surface or the back surface of the wiring board, but if necessary,
It may be provided as an inner layer inside the wiring board.

As the mounting substrate (also referred to as “base material” in the specification of the present application), a conventional substrate can be used as it is or with any improvement. Suitable substrates include, for example, a hard resin substrate, a metal-based substrate, a ceramic substrate, and a printed circuit board. The hard resin substrate is, for example, a substrate made of a resin reinforced with a reinforcing material such as glass fiber or Kevlar ^™ fiber, such as glass polyimide resin, glass epoxy resin, glass bismaleimide triazine (BT), glass polyphenylene ether (PPE) resin, or the like. The substrate is made of Metallic substrates are made of an organic insulating film (for example, polyimide resin,
A circuit pattern is formed via an epoxy resin or the like. Specifically, an IMS substrate, a metal core substrate,
An enamel substrate can be used. The ceramic substrate uses high-purity fine ceramic for the base material,
A circuit pattern is formed on this. Suitable ceramic substrates include, for example, an alumina substrate, an AlN substrate (aluminum nitride substrate), and a low-temperature sintered substrate. The printed circuit board includes various kinds of boards on which a circuit pattern is formed by a printed wiring technique, but is typically a built-up board. As is well known, the built-up board is a multilayer printed wiring board formed by sequentially laminating a conductor layer and an insulating layer on a base material by plating, screen printing, or the like.

In the wiring board of the present invention, pads for electrically connecting and mounting electronic components (particularly, electrode pads; hereinafter, referred to as "electronic component mounting pads"), routing wiring, external connection terminals, etc. The wiring elements of
It can be formed in any desired pattern using techniques common in this technical field. Wiring elements such as those described above can be formed using conventional techniques,
Usually, thin films or films of various common conductive metals such as copper and aluminum (hereinafter also referred to as metal layers).
It is preferable to form using. In consideration of conductivity, workability, and the like, it is particularly preferable to use a copper foil as a wiring element forming material. The thickness of the copper foil used here is usually about 10 to 30 μm, and a thickness of about 20 μm is preferable. In addition, the copper foil prevents oxidization of the copper foil so that a satisfactory connection cannot be made, or a wiring element (eg, lead, wiring, electrode, etc.) formed from the copper foil.
It is preferable to apply a conductive metal plating on one side or both sides to ensure the bonding between the metal and other parts. Suitable metal plating includes, for example, gold plating, silver plating,
Examples include tin plating and nickel plating. Gold plating is particularly preferred. Although the thickness of such metal plating can vary over a wide range,
Usually, it is around 1 μm.

Since the above-described copper foil is attached to the base material, a conventional adhesive can be used in the manufacture of a semiconductor device. A suitable adhesive is, for example, a thermosetting epoxy adhesive having excellent adhesion and heat resistance. The thickness of the adhesive layer formed from such an adhesive can be changed in a wide range depending on the type of adhesive to be used, the desired adhesive strength, and the like, but is usually about 10 to 40 μm. is there. The adhesive layer may be formed by applying a suitable adhesive from the solution, or may be formed by applying a sheet-like adhesive.

The copper foil adhered to the surface of the base material removes unnecessary portions thereof to form desired wiring elements, that is, leads, wiring, electrodes and the like. This step can be advantageously performed according to an etching process commonly used in the manufacture of semiconductor devices. That is, in order to mask a copper foil to be left as a wiring element, an etching resist is selectively coated on the copper foil, and then the exposed unnecessary copper foil is removed with an appropriate etching solution (for example, ferric chloride). Dissolved in water). If necessary, the above-described copper foil plating step may be performed following this etching step.

The wiring elements may be formed by sputtering, if necessary.
It can be formed in a desired pattern using a conventional thin film forming method such as an evaporation method. When such a film forming method is used, a wiring pattern having a thin and uniform film thickness can be formed with high precision, and the use of the above-mentioned adhesive is unnecessary. Film forming materials that can be advantageously used in such a method are also conductive metals such as copper and gold.

In the wiring board of the present invention, in order to reduce thermal stress caused by a difference in thermal expansion coefficient between the electronic component and the wiring board, and to secure enhanced connection reliability, the base material and the surface formed on the surface thereof are provided. Between the electronic component mounting pad and the routing wiring,
It is essential that a low elastic underlayer made of a material having a lower elastic modulus than the base material is interposed. When such a low elasticity underlayer exists, thermal stress caused by a difference in thermal expansion coefficient between the electronic component and the wiring board can be effectively reduced,
Further, since this is achieved through the improvement of the substrate as described above, it is possible to avoid complication of the device, unlike the conventional method relying on the improvement of the package.

For forming the low elasticity base layer, various low elasticity materials known to have a relatively low elastic modulus can be used. Suitable low-elasticity materials include, for example, thermosetting resins, for example, epoxy resins including NBR rubber and acrylic rubber, or thermoplastic resins, for example, polyolefin-based resins, polyimide resins, and the like.

Further, in such a low elastic material, a preferable range of the elastic modulus can be defined by Young's modulus. According to the knowledge obtained by the present inventors empirically, the low elastic underlayer contained in the wiring board is measured at room temperature (20 to 30 ° C.)
Preferably, it has a Young's modulus of less than 1 GPa and a Young's modulus of 10 MPa or less, measured at 150 ° C. If the measured Young's modulus is outside the above range, a satisfactory degree of stress relaxation cannot be achieved.

The low elasticity underlayer can be preferably formed by lamination of a sheet material, spin coating of a solution of a selected low elasticity material, or the like. Further, although the thickness of the low elasticity underlayer to be formed can be widely changed according to the region in which the underlayer is formed, a desired stress relaxation level, etc. In general, it is preferable to be as thin as possible from the viewpoint of easy formation of the element. Therefore, the thickness of the low elasticity underlayer is generally preferably in the range of 20 to 200 μm, and more preferably in the range of 25 to 50 μm.

In the wiring board of the present invention, after the low elasticity underlayer as described above is formed on the base material, pads for mounting electronic components and lead-out wirings are formed in accordance with the above-described method. Here, after forming the electronic component mounting pad and the lead wiring, the present inventors form a solder resist layer so as to cover such wiring elements. It has been found that it is more preferable to use a material having a relatively low elastic modulus, like the elastic underlayer. In addition to the functions and effects of the solder resist layer itself, for example, simplification of wiring, improvement of reliability, etc., by sandwiching wiring elements with a low elastic material, the intended stress relaxation effect can be further enhanced. Because. Therefore, the solder resist layer measures 1 GPa at room temperature (20-30 ° C.).
Having a Young's modulus of less than 10 and measured at 150 ° C.
It is preferable to be formed from a resist material having a Young's modulus of not more than MPa.

According to one preferred embodiment, in the wiring board of the present invention, the low elasticity underlayer is interposed between the base material of the wiring board and each of the electronic component mounting pad and the lead wiring. However, in particular, it extends to between the base material of the wiring board and the terminal for external connection, and in this case, the thickness of the low elastic underlayer in the area of the electronic component mounting pad and the wiring area is 50 μm or more. And the thickness of the low elasticity underlayer in the region of the external connection terminal is 10 μm.
It is more preferred that: In addition, it is usually preferable that a high elasticity underlayer is interposed between the base material of the wiring board and the external connection terminals, as described below. By forming the low-elasticity base layers with such different film thicknesses, the effect of stress relaxation can be further enhanced.

According to still another preferred embodiment, the wiring board of the present invention has external connection terminals on the base material in addition to the electronic component mounting pads and the lead-out wiring. Terminal is used as its base.
That is, between the base material of the wiring board and the external connection terminal,
It is more preferable to have a high elastic underlayer made of a material having a relatively high elastic modulus. The high elasticity underlayer usually extends to the region of the low elasticity underlayer described above,
It is preferable to be provided under the low elasticity base layer. In the wiring board, by placing a relatively hard and rigid layer on the inside as a base of the wiring element, and disposing a relatively soft and elastic layer on the front side,
The effect of stress relaxation can be further enhanced, and mounting of electronic components and the like can be performed more easily and more reliably. Therefore, it is necessary that the high elastic underlayer has at least a Young's modulus of 1 GPa or more measured at room temperature (20 to 30 ° C) and a Young's modulus of more than 10 MPa measured at 150 ° C. is there. The difference in Young's modulus between the low elasticity base layer and the high elasticity base layer is preferably as large as possible, but an extremely large difference may adversely affect the obtained stress relaxation and the film formation result. It is desirable to avoid.

The high elasticity underlayer can be formed according to the same method as the formation of the low elasticity underlayer described above. That is, it can be formed by laminating a sheet material such as an epoxy resin or a polyimide resin, which can satisfy the Young's modulus requirement as described above, on a base material. The material of the high elasticity underlayer may be the same as the material of the low elasticity underlayer described above, or may be a different material. Although the thickness of the high elastic underlayer can be widely varied depending on the region in which the underlayer is formed, the characteristics of the low elastic underlayer used in combination, the desired stress relaxation level, etc. , Preferably as thin as possible, and in general,
It is preferably in the range of 20 to 100 μm, and more preferably in the range of 20 to 50 μm.

Further, in the wiring board according to the present invention, at least one of the wiring elements of the wiring element is connected, for example, at one end between the wiring elements to which the wiring is connected. It is preferable to be formed non-linearly, especially on the low elasticity base layer between the electronic component mounting pad and the external connection terminal to which the other end is connected. Although the non-linear pattern of the routing wiring can be changed depending on the layer configuration of the wiring board or the like, it is usually preferable that the wiring be curved, and more specifically, such a pattern obtained by deformation of a cloud ruler or the like is used. Preferably, the pattern is arbitrarily curved. The routing wiring is not linear, and the low-elastic base layer underneath allows the wiring to be deformed in the planar direction.As a result, the wiring board can be arbitrarily adjusted without inconvenience such as disconnection. Since the device can be bent, the device can be made compact, and the workability and reliability at that time are good.

In the wiring board of the present invention, the electronic components mounted thereon include, as defined above, various components used in electronic devices and the like, and typically include a semiconductor chip or the like. is there. If the wiring boards are stacked and used, the electronic component may be the wiring board itself. Further, it is preferable that the electronic component is provided with a metal bump for establishing an electrical connection with the wiring board at a predetermined position. The distribution and number of the metal bumps can be arbitrarily changed according to the connection site and the number thereof.

The metal bump of the electronic component can be any metal bump generally used in the field of electronic packaging. The metal bump is usually formed on an electrode (for example, made of aluminum) of an electronic component. However, if necessary, the metal bump may be formed on a portion other than the electrode directly or through an appropriate conductive metal. You may. Metal bumps
Although not limited to those listed below, for example, gold (Au), nickel (Ni), copper (C
u), ball bumps formed by electrolytic plating, vapor deposition, or the like from high melting point solder (Pb / Sn), and stud bumps formed from gold (Au) by a wire bonding method. Of course, if a desired electrical connection can be obtained, the metal bump may not be present, or another connection medium may be provided instead of the metal bump.

The wiring board of the present invention has been described with reference to the preferred embodiments. However, the wiring board of the present invention can adopt any configuration other than the above within the scope of the present invention. For example, the wiring element
The present invention is not limited to the above-described electronic component mounting pad, routing wiring, and external connection terminal. Other wiring elements that can be incorporated include, for example, vias, pins, balls, and the like, which are usually considered part of the routing wiring.

The wiring board according to the present invention can be manufactured according to various procedures. According to one preferred embodiment, the wiring board of the present invention can form external connection terminals in a predetermined pattern on the base material. As described above, the external connection terminal can be formed by etching a conductive metal layer or the like.

Next, in accordance with the present invention, a method of exposing external connection terminals already formed on the base material of the wiring board to the base material of the wiring board has a lower elastic modulus than that of the base material. A low elastic underlayer made of a material is formed. As described above, the low elasticity base layer can be formed by laminating a low elasticity material sheet on the base material with a copper foil interposed therebetween.

After the low elasticity underlayer is formed as described above, the copper foil portion on the low elasticity underlayer is formed by etching in a pattern defined for each of the electronic component mounting pad and the lead wiring. I do. Note that, in the present invention, it is preferable to design the wiring so that the formed wiring is non-linear. Further, after forming the electronic component mounting pad and the lead-out wiring as described above, a solder resist layer made of a resist material having a low elastic modulus similar to the low elasticity base layer is formed so as to cover those portions. Is preferred.

The wiring board of the present invention can be usually manufactured through a series of steps as described above. However, the manufacturing method of the present invention can be arbitrarily changed or improved within the scope of the present invention, if necessary, by adopting a method generally used for manufacturing a wiring board. . In the method for manufacturing a wiring board according to the present invention, the formation of the external connection terminals is performed by forming a high elastic base layer made of a material having a higher elastic modulus than the base on the base of the wiring board. It is preferable that the external connection terminals be formed in a predetermined pattern on the high elasticity base layer. The formation region of the high-elastic underlayer on the base material may be entirely formed on the surface of the base material, or may be selectively formed, depending on factors such as a desired stress relaxation level. Although it is usually formed with a uniform film thickness, the film thickness of the high elasticity underlayer may be changed for each part as needed.

As previously described, in the practice of the present invention, the low modulus underlayer has a Young's modulus of less than 1 GPa measured at room temperature (20-30 ° C.) and measured at 150 ° C. It is preferably formed from a material having a Young's modulus of 10 MPa or less. Therefore, when the wiring board of the present invention is a printed board such as a built-up board, it is preferable to manufacture the wiring board according to the following procedure.

(1) A room temperature (20)
-30 ° C.) to form a low elastic underlayer made of a material having a Young's modulus of less than 1 GPa and less than 10 MPa measured at 150 ° C. The external connection terminals are already formed on this base material, preferably via a high elasticity underlayer, and the low elasticity underlayer is preferably formed by the external connection terminal as described above. It is performed without covering the terminal for use.

(2) A through hole is formed in a predetermined portion of the formed low elasticity underlayer, that is, in a portion where a connection via is to be formed, according to a method described in detail below. Due to the formation of the through-holes, pores are formed from the upper surface of the low elasticity underlayer toward the lower surface of the underlayer, and a conductor formed on or in the base material is formed on the bottom surface of the pores. Exposed.

(3) After the formation of the through-hole, the through-hole is filled with a conductive metal to form a connection via, and simultaneously with the process or at a different timing, a pad for mounting electronic components and a lead-out wiring are formed. . This step can be preferably performed by a plating step and a subsequent etching step, and both steps can be performed according to a conventional method. For example, in the plating step, the plating material may be copper, gold, or the like having excellent conductivity, and the plating method may be either electroless plating or electrolytic plating. As the plating thickness, an optimum thickness can be selected according to the type of the wiring element.

The step of forming the above-described through hole will be further described. The through-hole is usually formed in the entire thickness direction of the low elasticity base layer, and its end is closed by a conductor (wiring pattern) on the base material, so that the conductor is exposed on the bottom surface of the through-hole. Can be taken. However, if the conductor is formed inside the substrate,
It may be terminated at a conductor provided therein. The diameter of the through-hole can be widely varied depending on various factors, but is usually 0.05 to 0.5 mm
It is about.

The through-hole is advantageously formed by drilling using a CO ₂ laser, an excimer laser, or the like, or performing plasma etching in a state where a portion other than the through-hole is masked with a metal mask layer. Can be implemented. Further, when the wiring board of the present invention is a rigid board such as a hard resin plate, a metal plate, a ceramic plate or the like and has no wiring, it is preferable to manufacture according to the following procedure.

(1) A high elastic underlayer made of a material having a higher elastic modulus than the base material and a low elastic underlayer made of a material having a lower elastic modulus than the base material are formed on the base material of the wiring board. The conductive metal layer is sequentially formed in a region having a smaller area than the region of the elastic underlayer, and in a region having substantially the same area as the high elastic underlayer. The high elasticity underlayer and the low elasticity underlayer can each be formed as described above, and the conductive metal layer can also be formed by attaching a conductive metal foil or the like or forming a conductive metal as described above. Can be formed.

(2) By selectively removing the conductive metal layer formed in the previous step, the pads for mounting electronic parts, the routing wiring, and the terminals for external connection are formed in predetermined patterns. The selective removal of the conductive metal layer
As explained earlier, it can be done according to the usual method,
Preferably, it can be performed by etching. Otherwise, the wiring board of the present invention can be advantageously manufactured according to the following procedure.

(1) A low elastic underlayer made of a material having a lower elastic modulus than the base material and a high elastic underlayer made of a material having a higher elastic modulus than the base material are formed on the base material of the wiring board. The conductor metal layer is sequentially formed in a region having an area smaller than the region of the elastic underlayer, and in a region having substantially the same area as the low elastic underlayer. The high elasticity underlayer and the low elasticity underlayer can each be formed as described above, and the conductive metal layer can also be formed by attaching a conductive metal foil or the like or forming a conductive metal as described above. Can be formed.

(2) By selectively removing the conductive metal layer formed in the previous step, the pads for mounting electronic components, the routing wiring, and the terminals for external connection are formed in predetermined patterns. The selective removal of the conductive metal layer
As explained earlier, it can be done according to the usual method,
Preferably, it can be performed by etching. In carrying out such a manufacturing method, as described above, according to a desired stress relaxation level and the like,
The thickness of the high-elasticity underlayer and the thickness of the low-elasticity underlayer may be changed for each region, and by doing so, optimization of stress relaxation and the like can be achieved.

The above two manufacturing methods are different in that the occupied regions of the respective underlayers are different when the high elasticity underlayer and the low elasticity underlayer are formed on the base material. Sufficient stress relaxation can be achieved, thus realizing the effects unique to the present invention, for example, improvement of connection reliability, simplification of mounting work, utilization of conventional printed circuit board manufacturing technology or built-up technology, etc. can do.

The present invention also provides a semiconductor device in addition to the above-described wiring board. A semiconductor device according to the present invention includes a wiring board having an electronic component mounting pad having one end electrically connected to an electronic component, and a routing wiring having the other end connected to an external connection terminal; A semiconductor device including an electronic component electrically connected to and mounted on a pad for use in a semiconductor device, wherein the wiring substrate is formed of the wiring substrate of the present invention. In other words, in the semiconductor device of the present invention, a low elasticity material made of a material having a lower elastic modulus than the base material is provided between the base material of the wiring substrate serving as the base and each of the electronic component mounting pad and the lead wiring. The feature is that a stratum is interposed.

The basic configuration of the semiconductor device is not particularly limited, and can have the same configuration as a known semiconductor device. Further, as an extension of the scope of the present invention, other similar electronic devices can be used. Can be included. Also,
The semiconductor device of the present invention can be manufactured according to a method usually used for a semiconductor device. However, the wiring substrate is preferably manufactured according to the above-described method of the present invention.

More specifically, in the semiconductor device of the present invention, the electronic components mounted on the substrate are not particularly limited, and may be any components generally used for manufacturing semiconductor devices. Good. Suitable electronic components are
For example, it is a semiconductor chip such as an LSI chip and a VLSI chip. Although the size of such a semiconductor chip varies depending on the type, it is generally 40 to 5 mm.
It ranges from as thin as about 0 μm to as thick as about 500 μm.

Further, in the semiconductor device of the present invention, if necessary, at least one, usually two or more semiconductor chips are mounted on each base material,
A composite semiconductor device may be manufactured by being electrically connected to each other. Various types of semiconductor devices are included in the form of a composite semiconductor device. In general, it is preferable that devices of the same size are stacked by being stacked in the thickness direction, and each device is electrically connected. Such a combined semiconductor device is particularly useful as a memory module or the like.

The semiconductor device provided by the present invention comprises:
For example, the present invention can be advantageously used in mobile phones, personal computers, particularly portable personal computers, and other portable electric and electronic devices.

[0054]

Embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the illustrated embodiment is a typical example, and that various changes and improvements can be made within the scope of the present invention. FIG. 1 is a perspective view showing a wiring pattern on a surface of a wiring board according to a preferred embodiment of the present invention. As shown in the figure, the wiring board 10 has a lead-out wiring 17 on its upper surface, and terminates at an electronic component mounting pad 16 and an external connection terminal 12. Routing wiring 1
7, the pad 16 and the external connection terminal 12 are respectively
It is formed by performing etching after attaching a copper foil to a base material.

The configuration of the wiring board shown in FIG.
It can be easily understood from FIG. 2 which is a cross-sectional view along II-II. The wiring board 10 is manufactured using a rigid copper-clad laminate, and has conductor portions 2 formed by selective etching of copper foil on both surfaces of an insulating plastic base material 1. In addition, substrate 1
As shown in the figure, the conductor portions 2 on both sides are electrically connected by copper plated through holes. Substrate 1
On one surface of the terminal, a part of the conductor portion 2 is connected to an external connection terminal 1.
2 is formed, and the other portions are covered with a low elasticity underlayer 3 with a predetermined thickness. Low elastic underlayer 3
Is made of a thermosetting epoxy resin containing a rubber component (rubber-like material). A connection via 15 is formed at a predetermined portion of the low-elasticity base layer 3 to establish conduction with the conductor portion 2 formed thereunder. The connection via 15 is formed by plating the through hole with copper. On the surface of the low elasticity base layer 3, electronic component mounting pads 16 and lead-out wirings 17 formed by etching copper foil are formed in a pattern as shown in FIG. As a feature of the present invention, the routing wiring 17 is formed in a curved pattern so as to make the wiring substrate 10 movable. Further, in order to enhance the effect of relaxing the stress of the present invention, the base material 1 below the external connection terminal 12 itself is a highly elastic underlayer.

The wiring board of FIG. 2 can be advantageously manufactured by the method shown in FIG. First, step (A)
As shown in FIG. 1, conductor portions 2 are formed on both surfaces of an insulating plastic substrate 1 and one surface (the upper surface in the figure).
An external connection terminal 12 is formed on the substrate. For this step, a glass epoxy substrate 1 having a thickness of 1.0 mm and a copper (Cu) foil 2 having a thickness of 18 μm on both surfaces is prepared. Thereafter, through holes are formed in predetermined portions (two locations in the figure) of the base material 1 by drilling.

After the through-holes are formed, copper plating is performed in order to establish conduction between the Cu foils 2 on both sides of the base material 1 (which will be a conductor later). Here, after electroless copper plating,
Electroplating was performed using the Cu foil 2 as an electrode. The thickness of the copper plating was about 15 μm. After the copper plating of the through hole is completed, an unnecessary portion is dissolved and removed from the Cu foil 2 to form the conductor (wiring pattern) 2 and the external connection terminal 12. In this step, although not shown, an etching resist corresponding to a desired wiring pattern is applied on the Cu foil 2 and cured, and then the unnecessary Cu foil 2 not covered with the resist film is coated with an appropriate etchant (here, (Using an aqueous solution of ferric chloride). The used resist film is removed by dissolving with a suitable solvent.

Next, as shown in the step (B), the substrate 1
The low elastic underlayer 3 is formed in a predetermined thickness selectively on the surface of the substrate, that is, without covering the external connection terminals 12. Here, a 18 μm thick Cu foil 7 is placed on a thermosetting epoxy resin sheet (50 μm thick) 3 having rubber-like viscoelasticity, and then heated at 180 ° C. for 30 minutes under pressure (3 MPa). And laminated.

Subsequently, as shown in step (C), C
After a predetermined portion of the u-foil 7 is removed by etching, a through-hole 5 is formed in a predetermined portion of the low elasticity base layer 3 using the mask as a mask in order to establish conduction with the conductor portion 2 formed thereunder. The diameter of the through hole 5 was 100 μm, and was formed by CO ₂ laser drilling. Lastly, as shown in the step (D), the connection via 15 is formed by plating the through hole 5 of the low elasticity base layer 3 with copper. Further, the Cu foil 7 is selectively etched on the surface of the low elasticity base layer 3 so as to mount the electronic component mounting pad 16 and the lead wiring 17.
To form Through a series of steps as described above, the wiring board 10 as shown in FIG. 2 can be manufactured. It should be noted here that the manufacturing method of the present invention is based on the conventional printed wiring technology (formation of a conductor portion by patterning Cu foil) and build-up technology (for example, connection via by laser processing and electroless plating). This means that the conventional manufacturing process can be used, the manufacturing is simple, and the cost can be reduced.

FIGS. 4, 5, and 6 are cross-sectional views showing preferred embodiments of the built-up wiring board of the present invention. In any of the wiring boards, since the leading wiring is movable by arranging the high elastic underlayer and the low elastic underlayer in combination under the wiring pattern according to the present invention, remarkable stress relaxation and the connection reliability due thereto are achieved. The external connection terminals are formed on a material with high elasticity, making it easy and trouble-free to insert a memory into a slot or insert a card. can do. Note that each component of the illustrated wiring board can be basically the same as that of the wiring board 10 described above with reference to FIGS. 2 and 3, and thus, a detailed description here Is omitted.

In the wiring board 10 of FIG. 4, a highly elastic underlayer 4 having a predetermined thickness is formed on one surface of a plastic substrate 1 having a conductor portion 2 in a predetermined pattern. The low elasticity base layer 3 is formed so as to avoid the area of the external connection terminal 12. The wiring 17 and the external connection terminal 12 are formed so as to cover the high elasticity base layer 4 and the low elasticity base layer 3. Routing wiring 1
7 and the conductor 2 are electrically connected by the connection via 15. In such a laminated integrated structure, preferably, the high elasticity underlayer 4, the low elasticity underlayer 3, and the copper foil 7 for forming the wiring 17 and the conductor 2 are laminated, and then heated under pressure. , And cured (cured).

In the wiring board 10 shown in FIG. 5, a highly elastic underlayer 4 having a different thickness is formed on one surface of a plastic substrate 1 having a conductor portion 2 in a predetermined pattern. That is, the high elastic underlayer 4 is formed in a predetermined pattern such that the high elastic underlayer 4 in the region of the external connection terminal 12 is thick and the other regions are thin. The low elastic underlayer 3 is formed on the high elastic underlayer 4 so that the thickness of the high elastic underlayer 4 and the low elastic underlayer 3 is constant according to the maximum thickness. I have. And the high elasticity base layer 4
The external connection terminal 12 and the low elasticity base layer 3
The electronic component mounting pad 16 and the routing wiring 1
7 are formed respectively. The electronic component mounting pad 16 and the conductor 2 are electrically connected by the connection via 15. In addition, in the illustrated wiring board 10, through the use of a special manufacturing process, the wiring pattern surface is flattened instead of having a step on the wiring pattern surface as in FIG. 4. Has been improved.

The built-up wiring board 10 of FIG. 5 can be advantageously manufactured, for example, by the procedure shown in FIG. 7 in order. First, in step (A), conductor portions 2 are formed on both surfaces of a base material 1 of a built-up wiring board (in the drawing, formed wiring layers and the like are omitted for simplicity). Also, a through hole is formed as shown in the figure,
Copper plating is performed to establish conduction between the conductor portions 2 on both surfaces of the base material 1.

Next, as shown in the step (B), the substrate 1
A high elastic underlayer 4 is formed with a different thickness on the surface, a low elastic underlayer 3 is formed thereon with a predetermined thickness, and a copper foil 7 is further formed thereon. Here, in order to make the sum of the thickness of the high elastic underlayer 4 and the thickness of the low elastic underlayer 3 uniform and to make the surface of the underlayer flat, a low elasticity A method of laminating the material for forming the underlayer 3 on the high elasticity underlayer 4 and pressing strongly with an appropriate jig under heating can be advantageously used.

After the formation of the underlayer is completed, as shown in step (C), the electronic component mounting pad formed in the subsequent step and the conductor portion 2 formed under the low elasticity underlayer 3 are formed. A through-hole 5 is formed in a predetermined portion of the low elasticity base layer 3 in order to establish conduction. The through hole 5 can be advantageously formed by laser drilling. Lastly, as shown in the step (D), the connection via 15 is formed by plating the through hole 5 of the low elasticity base layer 3 with copper. Also,
The copper foil 7 is selectively etched on each of the surface of the low-elastic underlayer 3 and the surface of the high-elastic underlayer 4 in the same procedure as the formation of the conductor portion 2, and electronic components are mounted on the low-elastic underlayer 3. The external connection terminals 12 are formed on the high elasticity base layer 4 at the same time as forming the pads 16 and the routing wirings 17. Through a series of steps as described above, the wiring board 10 as shown in FIG. 5 can be manufactured.

In the wiring board 10 shown in FIG. 6, the high elastic underlayer 4 is formed only on the surface of the external connection terminal 12 on one surface of the plastic substrate 1 having the conductor 2 in a predetermined pattern. As shown in the drawing, the thickness of the high elastic base layer 4 is such that the end portion is thinner. The low elastic underlayer 3 is formed adjacent to the high elastic underlayer 4 with a thickness distribution as shown in the figure. In the case of the illustrated example, in particular, while the thickness of the low elasticity underlayer 3 is set to 50 μm or more, a part of the low elasticity underlayer 3 is formed under the very elastic underlayer 4 by a very small thickness (10 μm).
m or less). The thickness of the composite underlayer composed of the high elastic underlayer 4 and the low elastic underlayer 3 is constant. An external connection terminal 12 is provided on the high elastic base layer 4.
The electronic component mounting pad 1 is provided on the low elasticity base layer 3.
6 and the routing wiring 17 are formed respectively.
The electronic component mounting pad 16 and the conductor 2 are connected to the connection via 1
5 for conduction.

The wiring board 10 of FIG. 6 is the same as the wiring board 1 of FIG.
0 and thus can be similarly advantageously manufactured using the technique described above with reference to FIG. 8, 9 and 10 are cross-sectional views each showing a preferred embodiment of the wiring board of the present invention. The configuration of each wiring board 10 is different from that in which a rigid board is used as a base material and a wiring pattern is formed only on one side of the base material instead of the built-up wiring board shown in FIGS. 4, 5, and 6, except for Therefore, detailed description of each component of the illustrated wiring board will be omitted.

In the wiring board 10 shown in FIG. 8, a high elastic underlayer 4 is formed on one surface of a rigid plastic substrate 1 with a constant thickness, and a low elastic underlayer 3 is formed thereon.
Are formed avoiding the region of the external connection terminal 12. Then, the wiring 17 and the external connection terminals 12 are covered so as to cover the high elasticity base layer 4 and the low elasticity base layer 3.
Are formed. The routing wiring 17 and the conductor 2 are
The connection via 15 is conductive.

In the wiring board 10 shown in FIG. 9, a highly elastic underlayer 4 having a different thickness is formed on one surface of a rigid plastic substrate 1. That is, the high elastic underlayer 4 is formed in a predetermined pattern such that the high elastic underlayer 4 in the region of the external connection terminal 12 is thick and the other regions are thin. The low elastic underlayer 3 is formed on the high elastic underlayer 4 so that the thickness of the high elastic underlayer 4 and the low elastic underlayer 3 is constant according to the maximum thickness. I have. The external connection terminals 12 are formed on the high elasticity base layer 4, and the electronic component mounting pads 16 and the routing wirings 17 are formed on the low elasticity base layer 3. The electronic component mounting pad 16 and the conductor 2 are electrically connected by the connection via 15.

In the wiring board 10 shown in FIG. 10, the high elastic underlayer 4 is formed on one surface of the rigid plastic base material 1 only in the area of the external connection terminals 12. The low elastic underlayer 3 is formed adjacent to the high elastic underlayer 4 with a thickness distribution as shown in the figure. That is, the low elasticity base layer 3 includes the electronic component mounting pad 16 and the leading wiring 1.
While a thick film is formed in the region 7, a part of it is wrapped under the highly elastic underlayer 4 with a very small thickness. The thickness of the composite underlayer composed of the high elastic underlayer 4 and the low elastic underlayer 3 is constant. The external connection terminals 12 are provided on the high elasticity base layer 4, and the electronic component mounting pads 16 and the routing wirings 17 are provided on the low elasticity base layer 3.
Are formed respectively. Electronic component mounting pad 1
The conductor 6 is electrically connected to the conductor 2 by the connection via 15.

The wiring board 10 of FIG. 10 can be manufactured by using the method described above with reference to FIG. Hereinafter, the method of manufacturing the wiring board will be described step by step with reference to FIG. First, in a step (A), a high elasticity underlayer 4, a low elasticity underlayer 3, and a copper foil 7 are formed on one surface of a rigid plastic base material 1 in a predetermined thickness. Here, in order to make the sum of the thickness of the high elastic underlayer 4 and the thickness of the low elastic underlayer 3 uniform over the entire surface of the substrate 1 and to make the surface of the composite underlayer flat, It is possible to advantageously use a method in which a material for forming the low elasticity base layer 3 having a thickness larger than that of the above is laminated on the high elasticity base layer 4 and pressed strongly using an appropriate jig.

After the application of the copper foil is completed, as shown in step (B), the copper foil 7 is etched according to a desired wiring pattern, and unnecessary portions are dissolved and removed. The electronic component mounting pad 16 and the routing wiring 17 are formed on the low elasticity base layer 3, and at the same time, the high elasticity base layer 4 is formed.
Is formed on the external connection terminal 12, and thus the terminal 12 shown in FIG.
The wiring board 10 as shown in FIG.

FIG. 12 is a sectional view showing a preferred embodiment of the semiconductor device of the present invention. As can be understood from the figure, the wiring board 10 used in the semiconductor device 20
Is the same as the wiring board 10 described above with reference to FIG. The electronic component mounting pad 16 of the wiring board 10
A semiconductor chip (here, an LSI chip) 8 is mounted via a metal bump 9 made of gold (Au).
The metal bump 9 is attached to the lower surface of the semiconductor chip 8. In addition, such a semiconductor chip 8 with the bump 9 is commercially available as necessary.

[0074]

As described above, according to the present invention, the reliability of connection between pads of a wiring board and electronic components such as semiconductor chips can be increased without complicating the structure and manufacturing. The effect is obtained. More specifically, according to the present invention, a low-elasticity material layer is disposed below the electronic component mounting pad and the routing wiring, and between fixed points during mounting (lines of the routing wiring). Are connected non-linearly, so that stress caused by the difference between the thermal expansion coefficient of the mounting board and the thermal expansion coefficient of the electronic component can be reduced, connection reliability can be improved, and at the same time, Can be moved freely, so that the degree of freedom of implementation can be increased.

Further, since a material layer having a high elastic modulus is arranged under the external connection terminals of the wiring board, the operation of inserting a card such as a semiconductor device, specifically a memory or the like into a slot can be performed.
It can be easily performed by the conventional operation, and the reliability at that time is great. Furthermore, since the wiring board of the present invention has a simple structure and does not have a great difference compared with the conventional wiring board, it can be manufactured by a conventionally used printed board manufacturing technique or a built-up wiring technique.

Furthermore, according to the present invention, it is not necessary to package electronic components such as semiconductor elements in advance and then mount them on a wiring board, so that the cost of the module board and the like, the inductance, and the delivery time are reduced. Etc. can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a wiring pattern on a surface of a wiring board according to a preferred embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line II-II of the wiring board shown in FIG.

FIG. 3 is a sectional view sequentially illustrating a method of manufacturing the wiring board of FIG. 2;

FIG. 4 is a sectional view showing another preferred embodiment of the wiring board of the present invention.

FIG. 5 is a sectional view showing still another preferred embodiment of the wiring board of the present invention.

FIG. 6 is a sectional view showing still another preferred embodiment of the wiring board of the present invention.

FIG. 7 is a sectional view sequentially showing a method of manufacturing the wiring board of FIG. 5;

FIG. 8 is a sectional view showing still another preferred embodiment of the wiring board of the present invention.

FIG. 9 is a sectional view showing still another preferred embodiment of the wiring board of the present invention.

FIG. 10 is a sectional view showing still another preferred embodiment of the wiring board of the present invention.

FIG. 11 is a sectional view illustrating a method of manufacturing the wiring board of FIG. 10 in order.

FIG. 12 is a cross-sectional view showing a preferred embodiment of the semiconductor device of the present invention.

FIG. 13 is a sectional view showing an example of a conventional semiconductor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulating base material 2 ... Conductor part 3 ... Low elastic underlayer 4 ... High elastic underlayer 5 ... Through-hole 7 ... Copper foil 8 ... Semiconductor chip 9 ... Metal bump 10 ... Wiring board 12 ... External connection terminal 15 ... Connecting via 16 ... Pad for mounting electronic parts 17 ... Routing wiring 20 ... Semiconductor device

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme coat II (reference) H01L 23/12 NF term (reference) 5E314 AA27 BB02 BB11 FF05 GG11 5E319 AA03 AA07 AB05 AC11 AC16 GG11 5E346 AA12 FF45 HH07

Claims (12)

[Claims] An electronic component mounting pad electrically connected to an electronic component at one end, and a wiring substrate having a lead wiring connected to an external connection terminal at the other end, the wiring substrate comprising: a base material of the wiring substrate; A wiring substrate, wherein a low-elastic base layer made of a material having a lower elastic modulus than that of the base material is interposed between the electronic component mounting pad and the lead-out wiring. 2. A high elastic base layer made of a material having a higher elastic modulus than the base material is interposed between the base material of the wiring board and the external connection terminal. Item 2. The wiring board according to item 1. 3. The method according to claim 1, wherein the low elasticity underlayer is at room temperature (20 to 30).
C.), and is formed from a material having a Young's modulus of less than 1 GPa as measured at 150 ° C. and less than or equal to 10 MPa as measured at 150 ° C. 4. Wiring board. 4. The lead wiring is covered with a solder resist layer, the solder resist layer has a Young's modulus of less than 1 GPa measured at room temperature (20 to 30 ° C.), and has a Young's modulus of less than 150 ° C. The wiring board according to any one of claims 1 to 3, wherein the wiring board is formed from a resist material having a Young's modulus of 10 MPa or less as measured. 5. The low-elastic base layer extends between a base of the wiring board and the external connection terminal,
The thickness of the low-elastic underlayer in the region of the electronic component mounting pad and the routing wiring is 50 μm or more, and the thickness of the low-elastic underlayer in the region of the external connection terminal is 10 μm or less. The wiring substrate according to any one of claims 1 to 4, wherein 6. The wiring according to claim 1, wherein the routing wiring is formed non-linearly at least between the electronic component mounting pad and the external connection terminal.
The wiring board according to any one of the above. 7. A method of manufacturing a wiring board having one end having an electronic component mounting pad for electrically connecting an electronic component and the other end connected to an external connection terminal, the wiring board having: After forming a low-elastic base layer made of a material having a lower elastic modulus than the base on the pattern where the external connection terminals are exposed formed on the base, Forming the electronic component mounting pad and the lead-out wiring in a predetermined pattern, respectively. 8. After forming a high elastic base layer made of a material having a higher elastic modulus than the base on the base of the wiring board, the external connection layer is formed on the high elastic base. The method according to claim 7, wherein the terminals are formed in a predetermined pattern. 9. A room temperature (20 ° C.) on a substrate of the wiring board.
To form a low elastic underlayer made of a material having a Young's modulus of less than 1 GPa measured at 150 ° C and a Young's modulus of 10 MPa or less measured at 150 ° C. After forming a through hole at a predetermined portion from the upper surface of the underlayer to the wiring on the base located on the lower surface of the underlayer, a connection via in the through hole, the electronic component mounting pad The method for manufacturing a wiring board according to claim 7, wherein the wiring is formed by plating. 10. A method of manufacturing a wiring board having an electronic component mounting pad having one end electrically connected to an electronic component and a lead-out wiring having the other end connected to an external connection terminal, wherein the wiring board is provided. After forming a high elastic base layer made of a material having a higher elastic modulus than the base material, a low elastic base layer made of a material having a lower elastic modulus than the base material is formed on the base material. The electronic component mounting is performed by sequentially forming a conductive metal layer in a region narrower than the region of the underlayer and substantially in the same region as the high elasticity underlayer, and then selectively removing the conductive metal layer. Forming a wiring pad, the routing wiring, and the external connection terminal in a predetermined pattern, respectively. 11. A method for manufacturing a wiring board having a wiring for electronic components mounted on one end, the wiring being electrically connected to the electronic component, and the other end connected to a terminal for external connection, wherein the wiring substrate is provided. After forming a low-elastic base layer made of a material having a lower elastic modulus than the base material on the base material, the high-elastic base layer made of a material having a higher elastic modulus than the base material is formed on the low-elastic base layer. The electronic component mounting is performed by sequentially forming a conductive metal layer in a region narrower than the region of the underlayer and substantially in the same region as the low elasticity underlayer, and then selectively removing the conductive metal layer. Forming the wiring pads, the routing wirings, and the external connection terminals in predetermined patterns, respectively. 12. An electronic component mounting pad for electrically connecting an electronic component at one end, a wiring substrate having a lead wiring connected at the other end to an external connection terminal, and an electrical connection to the pad of the wiring substrate. In a semiconductor device including an electronic component connected to and mounted on, a lower elastic modulus than the base material between the base material of the wiring board and each of the electronic component mounting pad and the routing wiring. A semiconductor device having a low-elastic underlayer made of a material having the same interposed therebetween.